Results 111 to 120 of about 643,401 (321)

Push-and-Twist Drillstring Assemblies [PDF]

open access: yes, 2017
Deep drilling using a rigid drillstring requires the assembly and disassembly of multiple drill pipes. The interfaces between these pipes provide a challenge for automation because they must transmit large drilling forces and movements while, at the same
Firstbrook, David G.   +5 more
core  

Cryostratigraphy of Rhythmic Segregated Ice in Colluvium and Implications for Permafrost Slope Stability

open access: yesPermafrost and Periglacial Processes, EarlyView.
ABSTRACT The amount and stratigraphic setting of ground ice in permafrost slopes is a key control on the style and magnitude of permafrost mass wasting. Understanding the spatial and stratigraphic variations in ground ice distribution on permafrost slopes is therefore a fundamental property in assessing the stability of permafrost hillslopes.
Joseph M. Young   +2 more
wiley   +1 more source

Drill String Drag and Torque Test Device Design

open access: yesShiyou jixie, 2019
The existing drag and torque theoretical model has many assumptions, leading to a large difference between the calculated value and the true value, which seriously restricts the study of the mechanical behavior of the drill string and the optimization of
吴泽兵   +4 more
doaj  

Побудова математичної моделі компенсатора вертикальних переміщень бурильної колони підкронблочного типу [PDF]

open access: yes, 2014
Буріння свердловин в умовах надглибокого моря має низку особливостей в порівнянні із аналогічним процесом на суші, основною із яких є неможливість забезпечення стаціонарного положення бурової установки над свердловиною внаслідок її хитавиці.
Слабий, О. О.
core  

Subsurface Investigations of Cryo‐Hydrogeological Features in a High Arctic Catchment Under Transition

open access: yesPermafrost and Periglacial Processes, EarlyView.
ABSTRACT In this study, the internal structure and seasonal variations of cryo‐hydrogeological features were investigated in the Fuglebekken catchment, located near the Polish Polar Station Hornsund in Svalbard. Over a few years, rising air temperatures and intensified water circulation have significantly altered the distribution, extent, and state of ...
Wawrzyniak Tomasz   +3 more
wiley   +1 more source

Analysis of longitudinal, torsional and bending vibrations of drill string [PDF]

open access: yes, 2013
The paper considers longitudinal, torsional and bending vibrations of the drill string that occur during the bottom-hole deepening. The equations are presented that show the possibility of applying vibration velocity to evaluate the strength and ...
Hohol, V. I.   +2 more
core  

Delousing performance of ballan wrasse (Labrus bergylta) and lumpfish (Cyclopterus lumpus): seasonal consistency and the challenge of cryptic lice for lumpfish

open access: yesPest Management Science, EarlyView.
Ballan wrasse and lumpfish effectively reduce sea lice on salmon year round, although lumpfish struggle with cryptic lice, highlighting new considerations for lice management. Abstract BACKGROUND Cleaner fish play a crucial role in controlling caligid sea lice in Atlantic salmon aquaculture across the North Atlantic.
Adam Jonathan Brooker   +4 more
wiley   +1 more source

Shaping expectations, losing flexibility: A study of CEO promises as strategic communication tools

open access: yesStrategic Management Journal, EarlyView.
Abstract Research Summary CEO promises are powerful but understudied communication tools. We develop a dual‐mechanism framework theorizing that while CEO promises elevate stakeholder expectations, they simultaneously constrain strategic flexibility. We argue that CEO promise‐making is shaped by two competing pressures: making more promises when the ...
Majid Majzoubi   +2 more
wiley   +1 more source

Delineating seasonal shifts in reindeer habitat and diet selection by integrating GPS telemetry and stable isotope analysis

open access: yesWildlife Biology, EarlyView.
Seasonal changes shape herbivore behaviour by altering forage availability and habitat conditions; however, few studies integrate diet and habitat selection data across temporal scales. This study uses seasonality as a unifying framework to combine fine‐scale GPS‐based habitat selection data with broader‐scale dietary information from stable isotope ...
Tamara A. Hiltunen   +4 more
wiley   +1 more source

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